IV2

Rules and Guidelines Industrial ServicesGuideline for the Certification of Offshore Wind Turbines

1 General Conditions for Approval 2 Safety System, Protective and Monitoring Devices 3 Requirements for Manufacturers, Quality Management, Materials, Production and Corrosion Protection 4 Load Assumptions 5 Strength Analyses 6Structures 7 Machinery Components 8 Electrical Installations 9Manuals 10 Testing of Offshore Wind Turbines 11 Periodic Monitoring 12 Marine Operations 13 Condition Monitoring

Edition 2012

This Guideline was compiled by GL Renewables Certification in cooperation with the Wind and Marine Energy Committee. The Wind and Marine Energy Committee consists of representatives from public authorities, wind turbine and component manufacturers, engineering consultants, institutes, u niversities, technical associations and insurance companies. The current members of the Wind and Marine Energy Committee are named on our website: www.gl-group.com/GLRenewables

This Guideline comes into force on 1st December 2012 Interpretation of the Guideline is the exclusive prerogative of GL Renewables Certification. Any reference to the application of this Guideline is permitted only with the consent of GL Renewables Certification. GL Renewables Certification Germanischer Lloyd Industrial Services GmbH Renewables Certification Brooktorkai 18, 20457 Hamburg, Germany Phone: +49 40 36149-0 Fax: +49 40 36149-1720 glrenewables@gl-group.com www.gl-group.com/GLRenewables The latest edition of the General Terms and Conditions of Germanischer Lloyd Industrial Services GmbH is applicable. Reproduction by printing or photostatic means, even of extracts, is only permissible with the consent of GL Renewables Certification. Published by: GL Renewables Certification, Hamburg Typeset by: Guppy Design, Hamburg

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Table of Contents

List of Abbreviations Symbol and Units CChapter 1 General Conditions for Approval

1.1Scope.......................................................................................................................................................... 1-1 1.1.1General........................................................................................................................................................ 1-1 1.1.2 Transition periods....................................................................................................................................... 1-1 1.1.3Deviations................................................................................................................................................... 1-2 1.1.4 International standards and guidelines........................................................................................................ 1-2 1.1.5 Assessment documents............................................................................................................................... 1-2 1.1.6 Additional requirements............................................................................................................................. 1-2 1.1.7 Definitions................................................................................................................................................... 1-2 1.2 1.2.1 1.2.2 1.2.3 Extent of Certification.............................................................................................................................. 1-5 Subdivision of the certification................................................................................................................... 1-5 A- and B-Type Certificate for the type of an offshore wind turbine........................................................... 1-5 A- and B-Project Certificate..................................................................................................................... 1-13

1.3 Basic Principles for Design and Construction...................................................................................... 1-19 1.3.1General...................................................................................................................................................... 1-19 1.3.2 Definitions................................................................................................................................................. 1-19 1.3.3 Analysis procedure................................................................................................................................... 1-20 1.3.4 Mathematical model................................................................................................................................. 1-21 1.4 Risk-Based Design and Approval.......................................................................................................... 1-23 1.4.1General...................................................................................................................................................... 1-23 1.4.2 Definitions................................................................................................................................................. 1-23 1.4.3 Engineering analysis and approval process.............................................................................................. 1-26 Appendix 1.A 1.A IEC, CENELEC, ISO Standards, GL Guidelines and IMO/SOLAS Conventions.......................... 1-31 1.A.1General...................................................................................................................................................... 1-31 1.A.2 List of normative documents in the area of wind energy......................................................................... 1-31 1.A.3 List of ISO standards for offshore structures............................................................................................ 1-31 1.A.4 List of GL Rules and Guidelines.............................................................................................................. 1-32 1.A.5 IMO/SOLAS Conventions........................................................................................................................ 1-32 1.A.6 Supply sources.......................................................................................................................................... 1-33

CChapter 2

Safety System, Protective and Monitoring Devices

2.1General....................................................................................................................................................... 2-1 2.1.1General........................................................................................................................................................ 2-1 2.1.2 Assessment documents............................................................................................................................... 2-1 2.1.3 Fault consideration...................................................................................................................................... 2-2 2.1.4 Required risk reduction through protection functions................................................................................ 2-2

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2.2 Control and Safety System....................................................................................................................... 2-5 2.2.1General........................................................................................................................................................ 2-5 2.2.2 Definitions................................................................................................................................................... 2-5 2.2.3 Requirements and design concept ............................................................................................................. 2-8 2.2.4 Offshore applications................................................................................................................................ 2-10 2.3 Protective and Monitoring Devices....................................................................................................... 2-13 2.3.1General...................................................................................................................................................... 2-13 2.3.2 Limiting values, control system................................................................................................................ 2-13 2.3.3 Safety equipment (locking devices) for maintenance............................................................................... 2-21 Appendix 2.A 2.A Interaction of the Control and Safety Systems.................................................................................... 2-23

Appendix 2.B 2.B 2.B.1 2.B.2 Load Assessment Relevant Data............................................................................................................ 2-25 Turbine data relevant to load assessment.................................................................................................. 2-25 Shut-down parameters relevant to load assessment.................................................................................. 2-26

Appendix 2.C 2.C List of Protection Functions (Example)................................................................................................ 2-29

CChapter 3

Requirements for Manufacturers, Quality Management, Materials, Production and Corrosion Protection

3.1 Requirements for Manufacturers............................................................................................................ 3-1 3.1.1General........................................................................................................................................................ 3-1 3.1.2 Works equipment........................................................................................................................................ 3-1 3.1.3Personnel..................................................................................................................................................... 3-1 3.1.4 Shop approval............................................................................................................................................. 3-1 3.2 Quality Management................................................................................................................................ 3-3 3.2.1General........................................................................................................................................................ 3-3 3.2.2 Definitions................................................................................................................................................... 3-3 3.2.3 Requirements for the quality management system..................................................................................... 3-3 3.2.4 Certification of the QM system................................................................................................................... 3-3 3.3Materials.................................................................................................................................................... 3-5 3.3.1 General requirements.................................................................................................................................. 3-5 3.3.2 Metallic materials....................................................................................................................................... 3-6 3.3.3 Fibre-reinforced plastics (FRP)................................................................................................................ 3-16 3.3.4 Reinforced concrete and prestressed concrete.......................................................................................... 3-18 3.4 Production and Testing........................................................................................................................... 3-23 3.4.1 Fabrication and construction of steel structures....................................................................................... 3-23 3.4.2Welding..................................................................................................................................................... 3-27 3.4.3 Inspection and testing of steel structures.................................................................................................. 3-43 3.4.4 Laminating fibre-reinforced plastics......................................................................................................... 3-53 3.4.5 Adhesive bonding..................................................................................................................................... 3-56 3.4.6 Manufacturing surveillance for FRP......................................................................................................... 3-57 3.4.7 Production surveillance............................................................................................................................ 3-57 3.4.8 Making and working the concrete............................................................................................................ 3-58

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3.5 Corrosion Protection.............................................................................................................................. 3-65 3.5.1General...................................................................................................................................................... 3-65 3.5.2 Scope, application..................................................................................................................................... 3-65 3.5.3 Terms, definitions...................................................................................................................................... 3-65 3.5.4 Choice and suitability of corrosion p rotection systems............................................................................ 3-66 3.5.5 Design for corrosion protection................................................................................................................ 3-66 3.5.6 Material selection...................................................................................................................................... 3-67 3.5.7Coatings.................................................................................................................................................... 3-67 3.5.8 Metallic coatings and platings.................................................................................................................. 3-67 3.5.9 Corrosion protection of bolts.................................................................................................................... 3-68 3.5.10 Cathodic protection................................................................................................................................... 3-68 Appendix 3.A 3.A 3.A.1 Steels Suitable for Welded Offshore Structures................................................................................... 3-73 Preliminary remarks:................................................................................................................................ 3-73

Appendix 3.B 3.B 3.B.1 Thickness Limitations of Structural Steels........................................................................................... 3-75 Preliminary remarks:................................................................................................................................ 3-75

CChapter 4

Load Assumptions

4.1Fundamentals............................................................................................................................................ 4-1 4.1.1General........................................................................................................................................................ 4-1 4.1.2 Assessment documents............................................................................................................................... 4-1 4.1.3 Design methods.......................................................................................................................................... 4-3 4.1.4 Safety classes.............................................................................................................................................. 4-3 4.2 External Conditions.................................................................................................................................. 4-5 4.2.1General........................................................................................................................................................ 4-5 4.2.2 Wind conditions.......................................................................................................................................... 4-5 4.2.3 Marine conditions..................................................................................................................................... 4-13 4.2.4 Determination of other environmental conditions.................................................................................... 4-20 4.3 Design Basis and Site Assessment.......................................................................................................... 4-27 4.3.1General...................................................................................................................................................... 4-27 4.3.2 General wind farm location data............................................................................................................... 4-28 4.3.3 Meteorological data.................................................................................................................................. 4-28 4.3.4 Oceanographic data.................................................................................................................................. 4-30 4.3.5 Determination of the electrical power network conditions....................................................................... 4-32 4.3.6 Determination of the foundation/soil properties...................................................................................... 4-32 4.3.7 Determination of seismic conditions........................................................................................................ 4-32 4.3.8 Corrosion and erosion .............................................................................................................................. 4-32 4.3.9Temperature ............................................................................................................................................. 4-32 4.3.10 Wind farm influence................................................................................................................................. 4-33 4.4 Calculation of Loads............................................................................................................................... 4-35 4.4.1General...................................................................................................................................................... 4-35 4.4.2Loads......................................................................................................................................................... 4-35 4.4.3 Design situations and load cases............................................................................................................... 4-43 4.4.4 Design load cases for sea ice design situations........................................................................................ 4-55 4.4.5 Load assumptions for extreme temperatures............................................................................................ 4-55 4.4.6 Influence of earthquakes........................................................................................................................... 4-56 4.4.7 Variation of support structures natural frequency and operation within the resonance range ................ 4-58

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4.4.8 4.4.9

Clearance of structures............................................................................................................................. 4-58 Partial safety factors for loads.................................................................................................................. 4-59

4.5 Load-Relevant Control and Safety System Functions......................................................................... 4-61 4.5.1General...................................................................................................................................................... 4-61 4.5.2Scope......................................................................................................................................................... 4-61 4.5.3 LRF verification by controller model description (Alternative 1) ........................................................... 4-61 4.5.4 LRF verification by functional testing (Alternative 2) ............................................................................ 4-62 4.5.5 Transfer of controller from simulation stage to on-site offshore wind turbine......................................... 4-64 4.5.6 System version control............................................................................................................................. 4-64 4.5.7 Offshore applications to floating turbines................................................................................................. 4-64 Appendix 4.A 4.A 4.A.1 4.A.2 4.A.3 4.A.4 4.A.5 4.A.6 4.A.7 4.A.8 Descriptions and Coordinate Systems.................................................................................................. 4-65 Blade coordinate system........................................................................................................................... 4-65 Chord coordinate system.......................................................................................................................... 4-65 Hub coordinate system............................................................................................................................. 4-66 Rotor coordinate system........................................................................................................................... 4-66 Yaw bearing coordinate system................................................................................................................ 4-66 Support structure (tower) coordinate system............................................................................................ 4-66 Position-fixed coordinate system.............................................................................................................. 4-67 Water levels............................................................................................................................................... 4-67

Appendix 4.B 4.B 4.B.1 4.B.2 4.B.3 Evaluation of the Loads.......................................................................................................................... 4-69 Presentation of load case definitions......................................................................................................... 4-69 Presentation of the results......................................................................................................................... 4-69 Further evaluations................................................................................................................................... 4-70

Appendix 4.C 4.C Fault in the Power System...................................................................................................................... 4-73

Appendix 4.D 4.D 4.D.1 4.D.2 4.D.3 4.D.4 4.D.5 4.D.6 4.D.7 4.D.8 4.D.9 4.D.10 Design Parameters for Describing an Offshore Wind Turbine and Wind Farm.............................. 4-75 Turbine parameters .................................................................................................................................. 4-75 Support structure parameters ................................................................................................................... 4-75 Wind farm parameters .............................................................................................................................. 4-76 Geotechnical information and seismic conditions ................................................................................... 4-76 Wind conditions........................................................................................................................................ 4-76 Marine conditions..................................................................................................................................... 4-76 Conditions of the electrical power network.............................................................................................. 4-77 Other environmental conditions (where necessary)................................................................................. 4-78 Limiting conditions for maintenance, transport and installation.............................................................. 4-78 Deviations to Guideline parameters and models ..................................................................................... 4-78

Appendix 4.E 4.E Wind-Generated and Water-Depth-Limited Wave Spectra............................................................... 4-79

Appendix 4.F 4.F Directional Distribution of Waves in a Sea State................................................................................. 4-81

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Appendix 4.G 4.G Computation of Wave Kinematics......................................................................................................... 4-83 4.G.1General...................................................................................................................................................... 4-83 4.G.2 Linear wave theory................................................................................................................................... 4-84 4.G.3Stretching.................................................................................................................................................. 4-84 4.G.4 Stream function theories........................................................................................................................... 4-85 4.G.5 Constrained wave method ........................................................................................................................ 4-85 Appendix 4.H 4.H 4.H.1 4.H.2 Estimation of Design Wave Loads for Rigidly Positioned Structures ............................................... 4-87 Hydrodynamically transparent structures................................................................................................. 4-87 Hydrodynamically compact structures..................................................................................................... 4-88

Appendix 4.J 4.I Breaking Wave Loading on Piles........................................................................................................... 4-91

Appendix 4.J 4.J Wake and Wind Farm Turbulence........................................................................................................ 4-93

CChapter 5

Strength Analyses

5.1General....................................................................................................................................................... 5-1 5.2 5.2.1 5.2.2 5.2.3 5.2.4 Determination of the Stresses.................................................................................................................. 5-3 General notes on the loading of the structure............................................................................................. 5-3 Method of analysis...................................................................................................................................... 5-3 Dynamic calculation .................................................................................................................................. 5-5 Quasi-static calculation .............................................................................................................................. 5-5

5.3 Metallic Materials..................................................................................................................................... 5-7 5.3.1Application................................................................................................................................................. 5-7 5.3.2 Material properties...................................................................................................................................... 5-7 5.3.3 Static strength analysis............................................................................................................................... 5-7 5.3.4 Fatigue analysis.......................................................................................................................................... 5-8 5.3.5 Serviceability analysis.............................................................................................................................. 5-16 5.4 Concrete and Grout Materials............................................................................................................... 5-19 5.4.1General...................................................................................................................................................... 5-19 5.4.2 Ultimate limit states.................................................................................................................................. 5-19 5.4.3 Serviceability limit states.......................................................................................................................... 5-22 5.4.4 Prestressed concrete.................................................................................................................................. 5-22 5.4.5 Grouted connections................................................................................................................................. 5-23 5.5 Fibre Reinforced Plastics (FRP) and Bonded Joints........................................................................... 5-25 5.5.1General...................................................................................................................................................... 5-25 5.5.2Materials................................................................................................................................................... 5-25 5.5.3Analyses.................................................................................................................................................... 5-26 5.5.4 Glass fibre reinforced plastics (GRP)....................................................................................................... 5-29 5.5.5 Carbon fibre reinforced plastics (CRP)..................................................................................................... 5-31 5.5.6 Bonded joints............................................................................................................................................ 5-32

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Appendix 5.A 5.A Strength Analyses with the Finite Element Method............................................................................ 5-35 5.A.1General...................................................................................................................................................... 5-35 5.A.2 Modelling of the structure........................................................................................................................ 5-37 5.A.3 Loading of the structure............................................................................................................................ 5-40 5.A.4 Calculation and evaluation of the results.................................................................................................. 5-40 5.A.5 Documentation of FE analyses for the certification of wind turbines ..................................................... 5-41 Appendix 5.B 5.B Calculation of Synthetic S/N curves...................................................................................................... 5-45 5.B.1General...................................................................................................................................................... 5-45 5.B.2Documentation.......................................................................................................................................... 5-45 5.B.3 Calculation of S/N curve.......................................................................................................................... 5-46

CChapter 6Structures6.1 General Requirements.............................................................................................................................. 6-1 6.1.1Scope........................................................................................................................................................... 6-1 6.1.2 General design considerations.................................................................................................................... 6-1 6.1.3 Loads on the structure................................................................................................................................. 6-1 6.1.4 Serviceability limit state............................................................................................................................. 6-2 6.1.5Durability.................................................................................................................................................... 6-2 6.1.6 Model tests.................................................................................................................................................. 6-2 6.2 Rotor Blades.............................................................................................................................................. 6-3 6.2.1General........................................................................................................................................................ 6-3 6.2.2Documentation............................................................................................................................................ 6-3 6.2.3 Delivery checks.......................................................................................................................................... 6-3 6.2.4Analysis...................................................................................................................................................... 6-4 6.2.5 Blade tests................................................................................................................................................... 6-5 6.2.6 Rotor clearance........................................................................................................................................... 6-7 6.3 Machinery Structures............................................................................................................................... 6-9 6.3.1General........................................................................................................................................................ 6-9 6.3.2 Assessment documents............................................................................................................................... 6-9 6.3.3Analyses.................................................................................................................................................... 6-10 6.4 Nacelle Covers and Spinners..................................................................................................................6-11 6.4.1General.......................................................................................................................................................6-11 6.4.2 Assessment documents..............................................................................................................................6-11 6.4.3Analyses.....................................................................................................................................................6-11 6.4.4 Superstructural parts................................................................................................................................. 6-13 6.5Connections............................................................................................................................................. 6-15 6.5.1 Bolted connections.................................................................................................................................... 6-15 6.5.2 Grouted pile to structure connection......................................................................................................... 6-18 6.5.3 Tubular joint design.................................................................................................................................. 6-19 6.6 Steel Support Structures........................................................................................................................ 6-21 6.6.1 General design considerations.................................................................................................................. 6-21 6.6.2 Consideration of other regulations and guidelines................................................................................... 6-22 6.6.3 Assessment documents............................................................................................................................. 6-22 6.6.4 General design verification ...................................................................................................................... 6-22 6.6.5Stability..................................................................................................................................................... 6-24

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6.6.6Fatigue...................................................................................................................................................... 6-27 6.7 Concrete Support Structures................................................................................................................. 6-39 6.7.1General...................................................................................................................................................... 6-39 6.7.2 Assessment documents............................................................................................................................. 6-39 6.7.3 Ultimate limit state for strength................................................................................................................ 6-39 6.7.4 Dynamic analysis...................................................................................................................................... 6-39 6.7.5Stability .................................................................................................................................................... 6-39 6.7.6 Ultimate limit state for fatigue.................................................................................................................. 6-39 6.8 Foundation and Subsoil ......................................................................................................................... 6-41 6.8.1General...................................................................................................................................................... 6-41 6.8.2 Assessment documents............................................................................................................................. 6-41 6.8.3 Analysis concept....................................................................................................................................... 6-41 6.8.4 Loads to be applied................................................................................................................................... 6-41 6.8.5Foundation................................................................................................................................................ 6-42 6.8.6 Soil investigations and geotechnical report.............................................................................................. 6-42 6.8.7 Soil, general demands .............................................................................................................................. 6-42 6.8.8 Pile foundations........................................................................................................................................ 6-43 6.8.9 Gravity base foundations.......................................................................................................................... 6-46 6.9 6.9.1 6.9.2 Floating Structures................................................................................................................................. 6-49 Requirements for the analysis of floating structures................................................................................. 6-49 Mooring equipment requirements............................................................................................................. 6-49

Appendix 6.A 6.A 6.A.1 Detail Categories for the Fatigue Assessment...................................................................................... 6-51 Preliminary remarks.................................................................................................................................. 6-51

CChapter 7

Machinery Components

7.1General....................................................................................................................................................... 7-1 7.1.1 Assessment documents............................................................................................................................... 7-1 7.1.2Materials..................................................................................................................................................... 7-1 7.2 Blade Pitching System.............................................................................................................................. 7-3 7.2.1General........................................................................................................................................................ 7-3 7.2.2 Assessment documents............................................................................................................................... 7-3 7.2.3 Loads to be applied..................................................................................................................................... 7-3 7.2.4 Verification of the blade pitching system.................................................................................................... 7-4 7.3Bearings..................................................................................................................................................... 7-7 7.3.1General........................................................................................................................................................ 7-7 7.3.2 Assessment documents............................................................................................................................... 7-7 7.3.3Materials..................................................................................................................................................... 7-7 7.3.4 Loads to be applied..................................................................................................................................... 7-7 7.3.5Calculations................................................................................................................................................ 7-8 7.3.6Miscellaneous........................................................................................................................................... 7-10 7.4Gearboxes.................................................................................................................................................7-11 7.4.1General.......................................................................................................................................................7-11 7.4.2 Assessment documents..............................................................................................................................7-11 7.4.3Materials....................................................................................................................................................7-11 7.4.4 Loads to be applied....................................................................................................................................7-11 7.4.5 Calculation of load capacity of gears........................................................................................................ 7-12

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7.4.6 Strength analysis for shafts and connecting elements.............................................................................. 7-15 7.4.7 Additional verifications............................................................................................................................ 7-15 7.4.8Equipment................................................................................................................................................. 7-15 7.4.9 Inspection of gearboxes............................................................................................................................ 7-16 7.4.10Running-in................................................................................................................................................ 7-16 7.4.11Manuals..................................................................................................................................................... 7-16 7.5 Mechanical Brakes and Locking Devices............................................................................................. 7-17 7.5.1Brakes....................................................................................................................................................... 7-17 7.5.2 Locking devices........................................................................................................................................ 7-18 7.6Couplings................................................................................................................................................. 7-19 7.6.1General...................................................................................................................................................... 7-19 7.6.2 Assessment documents............................................................................................................................. 7-19 7.6.3Materials................................................................................................................................................... 7-19 7.6.4 Verifications.............................................................................................................................................. 7-19 7.7 Elastomer Bushings................................................................................................................................ 7-21 7.7.1General...................................................................................................................................................... 7-21 7.7.2 Assessment documents............................................................................................................................. 7-21 7.7.3 Loads to be applied................................................................................................................................... 7-21 7.7.4 Verifications.............................................................................................................................................. 7-21 7.7.5Miscellaneous........................................................................................................................................... 7-21 7.8 Yaw System.............................................................................................................................................. 7-23 7.8.1General...................................................................................................................................................... 7-23 7.8.2 Assessment documents............................................................................................................................. 7-23 7.8.3 Loads to be applied................................................................................................................................... 7-23 7.8.4 Verification of the yaw system.................................................................................................................. 7-24 7.9 Hydraulic Systems.................................................................................................................................. 7-27 7.9.1General...................................................................................................................................................... 7-27 7.9.2 Assessment documents............................................................................................................................. 7-27 7.9.3Materials................................................................................................................................................... 7-27 7.9.4 Design and construction........................................................................................................................... 7-27 7.10 Drive Train Dynamics............................................................................................................................. 7-29 7.10.1General...................................................................................................................................................... 7-29 7.10.2 Method of analysis.................................................................................................................................... 7-29 7.10.3Documentation.......................................................................................................................................... 7-30 7.11 Offshore Application............................................................................................................................... 7-31 7.11.1General...................................................................................................................................................... 7-31 7.11.2Atmosphere............................................................................................................................................... 7-31 7.11.3Covering................................................................................................................................................... 7-31 7.11.4 Corrosion Protection................................................................................................................................. 7-31 7.11.5 Surface preparation for protective coatings.............................................................................................. 7-32 7.11.6Miscellaneous........................................................................................................................................... 7-32 Appendix 7.A 7.A Drive Train Dynamics............................................................................................................................. 7-33 7.A.1General...................................................................................................................................................... 7-33 7.A.2 Modelling of the system........................................................................................................................... 7-33 7.A.3 Calculation and evaluation of the results.................................................................................................. 7-35 7.A.4 Extended evaluation.................................................................................................................................. 7-35 7.A.5Documentation ......................................................................................................................................... 7-36

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Appendix 7.B 7.B Supplementary Measurements for the Evaluation of the Drive Train Dynamics............................. 7-39 7.B.1Scope......................................................................................................................................................... 7-39 7.B.2Applications.............................................................................................................................................. 7-39 7.B.3Measurements........................................................................................................................................... 7-40 7.B.4Documentation.......................................................................................................................................... 7-40

CChapter 8

Electrical Installations

8.1 Area of Application .................................................................................................................................. 8-1 8.1.1Application................................................................................................................................................. 8-1 8.1.2Scope........................................................................................................................................................... 8-1 8.1.3Standards..................................................................................................................................................... 8-1 8.1.4 Operating and environmental conditions.................................................................................................... 8-1 8.1.5 General design requirements...................................................................................................................... 8-2 8.1.6 Parallel operation with public power supply networks............................................................................... 8-3 8.1.7 Assessment documents............................................................................................................................... 8-3 8.1.8 Stand-alone operation................................................................................................................................. 8-5 8.2 Electrical Machines.................................................................................................................................. 8-7 8.2.1General........................................................................................................................................................ 8-7 8.2.2 Rating of generators.................................................................................................................................... 8-7 8.2.3 Rating of auxiliary motors.......................................................................................................................... 8-7 8.2.4Materials..................................................................................................................................................... 8-7 8.2.5 Ventilation and cooling............................................................................................................................... 8-8 8.2.6Windings..................................................................................................................................................... 8-8 8.2.7 Bearings and couplings............................................................................................................................... 8-8 8.2.8 Generator testing......................................................................................................................................... 8-8 8.2.9Earthing....................................................................................................................................................... 8-9 8.2.10 Carbon brushes........................................................................................................................................... 8-9 8.3 Power Transformers................................................................................................................................8-11 8.3.1General.......................................................................................................................................................8-11 8.3.2Installation.................................................................................................................................................8-11 8.3.3Protection...................................................................................................................................................8-11 8.3.4 Dry-type power transformers.................................................................................................................... 8-12 8.3.5 Liquid-immersed power transformers...................................................................................................... 8-12 8.4 Frequency Converters............................................................................................................................ 8-13 8.4.1General...................................................................................................................................................... 8-13 8.4.2 General design and data to be provided.................................................................................................... 8-13 8.4.3 Protection equipment ............................................................................................................................... 8-15 8.4.4 Routine testing.......................................................................................................................................... 8-16 8.4.5 Measurement and type testing.................................................................................................................. 8-17 8.4.6 Installation, commissioning and maintenance.......................................................................................... 8-17 8.4.7 Frequency converters connected to other systems than generator ........................................................... 8-18 8.5 Medium-voltage Switchgear.................................................................................................................. 8-19 8.5.1General...................................................................................................................................................... 8-19 8.5.2 Protective measures and tests................................................................................................................... 8-19 8.5.3 Pressure relief........................................................................................................................................... 8-19 8.5.4 SF6 switchgear.......................................................................................................................................... 8-19 8.6 Back-up Power Supply System.............................................................................................................. 8-21 8.6.1General...................................................................................................................................................... 8-21

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8.6.2 8.6.3 8.6.4 8.6.5

Charging equipment.................................................................................................................................. 8-21 Energy storage system.............................................................................................................................. 8-21 Installation and operation of batteries....................................................................................................... 8-21 Back-up power supply for long periods.................................................................................................... 8-22

8.7 Low-voltage Switchgear, Controlgear and Switchboards................................................................... 8-23 8.7.1General...................................................................................................................................................... 8-23 8.7.2Protection.................................................................................................................................................. 8-23 8.7.3 Switching devices..................................................................................................................................... 8-24 8.7.4 Distribution panels.................................................................................................................................... 8-24 8.7.5 Electrical apparatus................................................................................................................................... 8-25 8.7.6 Control, measuring and indicating circuits............................................................................................... 8-25 8.7.7 Safety-related parts according to 2.1.4..................................................................................................... 8-25 8.8 Cables, Lines and Accessories................................................................................................................ 8-27 8.8.1General...................................................................................................................................................... 8-27 8.8.2 Selection of cables, lines and accessories................................................................................................. 8-27 8.8.3Documents to be submitted for A-Design Assessment............................................................................. 8-27 8.8.4 Loading and protection of cables and lines.............................................................................................. 8-27 8.8.5 Laying and installation of cables and lines............................................................................................... 8-28 8.9 Lightning Protection............................................................................................................................... 8-29 8.9.1General...................................................................................................................................................... 8-29 8.9.2 Basic design criteria.................................................................................................................................. 8-29 8.9.3 Lightning protection of sub-components.................................................................................................. 8-30 8.10 Offshore Wind Farm Installations........................................................................................................ 8-35 8.10.1General...................................................................................................................................................... 8-35 8.10.2 Transformer platform installations........................................................................................................... 8-35 8.10.3 Wind farm cabling.................................................................................................................................... 8-35 8.10.4 Cable connecting the feeders of offshore wind turbines........................................................................... 8-36 Appendix 8.A 8.A Generator Parameters for Electrical Calculations and Simulations................................................. 8-37

CChapter 9Manuals9.1 Sea Transport and Offshore Installation Manual.................................................................................. 9-1 9.1.1General........................................................................................................................................................ 9-1 9.1.2 Objective and format of the manual for sea transport and offshore installation......................................... 9-1 9.1.3 Scope of the manual for sea transport and offshore installation................................................................. 9-1 9.2 Commissioning Manual............................................................................................................................ 9-5 9.2.1General........................................................................................................................................................ 9-5 9.2.2 Format of the commissioning manual........................................................................................................ 9-5 9.2.3 Scope of the commissioning manual.......................................................................................................... 9-5 9.3 9.3.1 9.3.2 9.3.3 Operating Manual.................................................................................................................................... 9-9 Purpose of the operating manual................................................................................................................ 9-9 Format of the operating manual.................................................................................................................. 9-9 Scope of the operating manual................................................................................................................... 9-9

9.4 Maintenance Manual...............................................................................................................................9-11 9.4.1General.......................................................................................................................................................9-11 9.4.2 Format of the maintenance manual............................................................................................................9-11 9.4.3 Scope of the maintenance manual.............................................................................................................9-11

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CChapter 10 Testing of Offshore Wind Turbines10.1General..................................................................................................................................................... 10-1 10.1.1 Prototype test............................................................................................................................................ 10-1 10.1.2 Tests within the scope of the Design Assessment..................................................................................... 10-2 10.2 10.3 10.4 Power Curve............................................................................................................................................ 10-5 Noise Emission........................................................................................................................................ 10-7 Electrical Characteristics....................................................................................................................... 10-9

10.5 Test of Turbine Behaviour.....................................................................................................................10-11 10.5.1General.....................................................................................................................................................10-11 10.5.2 Test plan...................................................................................................................................................10-11 10.5.3 Test of the safety system..........................................................................................................................10-11 10.5.4 Test of the braking systems......................................................................................................................10-11 10.5.5 Test of automatic operation..................................................................................................................... 10-13 10.5.6 Test of the switching operations............................................................................................................. 10-13 10.5.7 Measurement of the natural frequencies................................................................................................. 10-14 10.5.8 Hydraulic pressure at the mechanical brakes.......................................................................................... 10-14 10.6 Load Measurements............................................................................................................................. 10-15

10.7 Prototype Tests of Gearboxes............................................................................................................... 10-17 10.7.1General.................................................................................................................................................... 10-17 10.7.2 Scope of the prototype test at the test bench........................................................................................... 10-17 10.7.3 Scope of the prototype test at the offshore wind turbine........................................................................ 10-18 10.7.4 Documentation of the prototype tests..................................................................................................... 10-18 10.8 Witnessing of the Commissioning....................................................................................................... 10-19 10.8.1General.................................................................................................................................................... 10-19 10.8.2 Procedure for witnessing........................................................................................................................ 10-19 10.8.3 Scope of inspection for electrical engineering......................................................................................... 10-19 10.9 Inclining Test of Floating Offshore Wind Turbines........................................................................... 10-21

CChapter 11 Periodic Monitoring11.1 Scope and Execution................................................................................................................................11-1 11.1.1General.......................................................................................................................................................11-1 11.1.2 Scope and execution..................................................................................................................................11-1 11.2 Technical Experts, Documentation and Actions...................................................................................11-3 11.2.1 Technical experts.......................................................................................................................................11-3 11.2.2Documentation...........................................................................................................................................11-3 11.2.3Actions.......................................................................................................................................................11-3

CChapter 12 Marine Operations12.1General..................................................................................................................................................... 12-1 12.2Loadout.................................................................................................................................................... 12-3 12.2.1 Basic information...................................................................................................................................... 12-3 12.2.2 Choice of loadout type.............................................................................................................................. 12-3

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12.2.3

Detailed investigation of loadout operation.............................................................................................. 12-4

12.3Transportation........................................................................................................................................ 12-5 12.3.1Seafastening.............................................................................................................................................. 12-5 12.3.2Towing...................................................................................................................................................... 12-5 12.4 Lifting Operations.................................................................................................................................. 12-7 12.4.1General...................................................................................................................................................... 12-7 12.4.2 Lifting arrangements................................................................................................................................. 12-7 12.4.3 Offshore cranes and crane barges............................................................................................................. 12-7 12.4.4 Monitoring, measurements....................................................................................................................... 12-7 12.5 12.5.1 12.5.2 12.5.3 12.5.4 12.6 12.6.1 12.6.2 Installation Offshore............................................................................................................................... 12-9 Jacket installation...................................................................................................................................... 12-9 Pile installation....................................................................................................................................... 12-10 Installation of gravity-based foundations............................................................................................... 12-10 Topside installation..................................................................................................................................12-11 Other Procedures.................................................................................................................................. 12-13 Vessel positioning .................................................................................................................................. 12-13 Pipe/cable laying.................................................................................................................................... 12-13

CChapter 13 Condition Monitoring13.1General..................................................................................................................................................... 13-1 13.2 Offshore Application............................................................................................................................... 13-3

IV Part 2 GL 2012

List of Abbreviations

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List of Abbreviations

Abbreviation A AC C CD CMS Coh CQC CRP CTI DAF DC DLC DOF DP E EC ECD EIS EMC EOG ETM EWM EWS F FAT FLS FEM FMEA FRP GCC GL GRP HAT HMI HRC HSWL IGCC IOPPC IPE

Meaning Abnormal (for partial safety factors) Alternating Current Condition of the serviceability Chart Datum Condition Monitoring System Coherence function Complete Quadratic Combination Carbon fibre Reinforced Plastic Comparative Trackig Index Dynamic Amplification Factor Direct Current Design Load Case Degrees Of Freedom Dynamic Positioning Extreme (for partial safety factors) Eurocode Extreme Coherent gust with Direction change Electrical Insulation System Electromagnetic Compatibility Extreme Operating Gust Extreme Turbulence Model Extreme Wind speed Model Extreme Wind Shear Fatigue Factory Acceptance Test Fatigue Limit State Finite Element Method Failure Mode and Effect Analysis Fibre Reinforced Plastic Grid Code Compliance Germanischer Lloyd Glass fibre Reinforced Plastic Highest Astronomical Tide Human Machine Interface Rockwell Hardness Highest Still Water Level International Grid Code Compliance International Oil Pollution Prevention Certificate Implementation of design-related requirements in Production and Erection

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List of Abbreviations

IV Part 2 GL 2012

ITP ITU JONSWAP LAT LDD LEMP LPL LPZ LRF LSWL MBL MIS MQ MSL MUL N NDE NDT NTM NWP OTDR OVC PC PV PSCS PWB QM RCD RCM RMS ROV SPD S SLS SRP/CS T TC THD TLP TMCP TT U, ULS WPQ WPS

Inspection and Test Plan International Telecommunication Union Joint North Sea Wave Atmosphere Program Lowest Astronomical Tide Load Duration Distribution Lightning Electromagnetic impulses Lightning Protection Level Lightning Protection Zone Load-Relevant control and safety system Functions Lowest Still Water Level Minimum Breaking Load Wind, wave and current Misalignment Material Quality Mean Sea Level Multidirectionality of metocean conditions Normal (for partial safety factors) Non-Drive End Non Destructive Testing Normal Turbulence Model Normal Wind Profile Optical Time Domain Reflectometry Overvoltage Category Project Certificate Photovoltaic Power Semiconductor Converter System Printed Wiring Board Quality Management Residual Current-operated protective Devices Residual Current Monitoring devices Root Mean Square Remote Operated Vehicle Surge Protection Devices Wind turbine class S Serviceability Limit State Safety-related Parts of Control System Transport, erection and maintenance (for partial safety factors and for the wind speed) Type Certificate Total Harmonic Distortion Tension Leg Platform Thermo-Mechanically Controlled Processed Test Temperature Ultimate Limit State Welding Procedure Qualification Welding Procedure Specifications

IV Part 2 GL 2012

Symbol and Units

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Symbol and Units

Symbols and Units Used in the Guideline Symbol A A Ap AS a a aISO B B Bz0 b C C C C() CA CD CW CM CM Cia Cib Cic Cid CIFF CT c c D D, d D DQ DF d di dU/dt Meaning cross-section area (strength) reference surface (the projected area) category for the higher turbulence intensity end area of scour skirt stress cross-section centre distance throat thickness of fillet welds live modification factor category for the medium turbulence intensity size reduction factor for the models of extreme operating gust, extreme direction change and extreme wind shear tool offset width (breadth) category for lower turbulence intensity scale parameter of the Weibull function wave celerity normalising factor used for the JONSWAP spectrum coefficient of aerodynamic lift drag coefficient coefficient of aerodynamic drag coefficient of aerodynamic moment inertia (added mass) coefficient reduction factor for the material safety factor, short-term strength reduction factor for the material safety factor, fatigue strength reduction factor for the material safety factor, stability reduction factor for the material safety factor, bonding reduction factor for inter-fibre failure thrust coefficient spring rate blade chord length damage diameter (e.g. of rotor, pile, bolt) generator damping coefficient damage contribution from vortex-induced transverse vibrations damage contribution of the actions from the operating conditions water depth distance to neighbouring wind turbine voltage change rate Unit m2 m2 m2 mm mm mm m, mm m/s m/s N/m m m, mm m kV/s

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Symbol and Units

IV Part 2 GL 2012

Symbol E E e F F(Hs) Fi Fi FM Fperm FSmax F0,2min Fx f f fa ft fc fm fR fw fi fc fLASH fck ff fn fpe f0,n fE fN fR fR,m fy fu G(e) g H, h HB HD Hm Hs HsT H0 H1/3

Meaning E-modulus (modulus of elasticity) energy misalignment force marginal probability distribution function of wave heights force acting in the direction i = x, y or z impact force inertia force permissible lashing force max. bolt force under extreme load bolt force at the 0.2% elastic strain limit initial equivalent misalignment line force frequency correction factor for misalignment effects correction factor for plate thickness correction factor for corrosion effects correction factor for material effects correction factor for mean stress effect correction factor for weld shape effect correction factor for importance of structural element compressive strength (concrete) safety factor for lashing with wire ropes characteristic cylinder compressive strength profile form error rated frequency normal pitch error n-th natural frequency excitation frequencies of drive train natural (eigen-)frequencies of wind turbine rotating frequency transition frequency of the m rotor blades yield strength tensile strength directional distribution function acceleration due to gravity (= 9.81m/s) height, wave height breaking wave height design wave height generator inertia constant significant or modal wave height maximum significant wave height the service vessel is allowed to operate height of the deep water wave average of the 1/3 highest waves

Unit MPa, N/mm2 Nm mm N N N N N N N m N/m 1/s MPa, N/mm2 MPa, N/mm2 m Hz m 1/s 1/s 1/s 1/s 1/s MPa, N/mm2 MPa, N/mm2 m/s2 m, mm m m kWs/kVA m m m m

IV Part 2 GL 2012

Symbol and Units

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Symbol H1% ha0* *

Meaning wave height with a probability of exceedance equal to 0.01 coefficient of tool addendum utilized dedendum coefficient of tool coefficient of tool dedendum moment of inertia turbulence intensity characteristic value of the turbulence intensity for a mean wind speed of 15 m/s characteristic turbulence intensity of the wind speed effective turbulence intensity peak short-circuit current initial symmetrical short-circuit current casting quality level constant Keulegan-Carpenter number application factor transverse load factor, scuffing face load factor, scuffing transverse load factor, root stress face load factor, root stress transverse load factor, contact stress face load factor, contact stress dynamic factor load distribution factor shape parameter of the Weibull function average thickness of the hard marine growth reduction factor for the design S/N curve of large bolts length basic rating life modified rating life modified reference rating life upper still water level lower still water level height of wave crest height of wave trough water level safety for run up moment braking moment moment acting in the direction i = x, y or z tilting moment of the induction generator, breakdown torque rated torque mass slope parameter of the S/N curve variance of the wave spectra n-th order moments of the spectrum

Unit m m4 A A m m h h h m m m m m Nm Nm Nm Nm kN kg m2 -

hFfP0 hfP0* I I I15 Ic Ieff ip I k j j0 K KA KB KB KF KF KH KH Kv K k k ks

L, l, L10 L10m L10mr Lu SW Ll SW Lu WA Ll WA Lsafety M MB Mi Mk Mn m m m0 mn

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Symbol and Units

IV Part 2 GL 2012

Symbol mn N N N N Ni NSS50 n n n n1 n2 n3 n4 nA ni nmax nr nref P P P P PA PR (Vhub) Pr PT P PW (Vhub) p pr pmax p(V) Q q q qi qc R R R, r Ra RaF RaH Re

Meaning normal module total number or revolutions permissible load cycle number normal or perpendicular force (axial force) recurrence period for extreme conditions tolerable number of stress cycles number of sea states with a duration of 3 hours in 50 years quantity (i.e. number of) notch sensitivity rotational speed minimum operating (rotational) speed set value of the (rotational) speed controller maximum (rotational) operating speed cut-out (rotational) speed activation (rotational) speed number of revolutions maximum (rotational) overspeed rated (rotational) speed reference load cycle number power confidence level dynamic bearing load number of poles activation power Rayleigh probability distribution, i.e. the probability that V < Vo rated power over-power survival probability Weibull probability distribution pressure protuberance maximum contact stress probability density function (hereof the wind speed) accuracy acc. to ISO area loading machining allowance time share on the i-th load level cone penetration resistance resistance stress or strain ratio radius arithmetic surface roughness mean peak to valley roughness of root mean peak to valley roughness of flank Reynolds number

Unit mm N a 1/min 1/min 1/min 1/min 1/min 1/min 1/min 1/min W N kW kW kW N/m2 mm N/mm2 N/m2 mm kN/m2 N, Nm, MPa m m m m -

IV Part 2 GL 2012

Symbol and Units

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Symbol Rm Rp0.2 Rz ra rr rs S S S(1.0)* S(1.2)* Sd SintS Smin STest SA SB SF SH Sk,M Sk,A Sn SP S0 S1 (f) S () S s sK T T T1 TD TD Ta = 2H Tp Tref Tz t t Uc(z) Uc, sub Uc, wind UD Ui

Meaning tensile strength yield strength (0.2% proof stress) surface roughness armature resistance rotor resistance stator resistance action safety 1 saturation factorst

Unit N/mm2 N/mm2 m N, Nm, MPa N N, Nm, MPa, N, Nm, MPa, kVA m2/s2 m2/s C, K s s s kWs/kVA s s s m, mm s m/s m/s m/s m/s -

2 saturation factornd

reduction factor casting quality safety factor for scuffing (integral temperature method) minimum safety factor test load safety factor for micropitting safety factor for scuffing (flash temperature method) safety factor for tooth breakage safety factor for pitting mean value of the characteristic actions amplitude of the characteristic actions generator rated power reduction factor survival probability static safety factor power spectral density wave (energy) spectrum safety factor for micropitting sea floor slope tilting or breakdown slip temperature time interval mean (characteristic) wave period of the sea state design temperature design wave period mechanical starting time (2 x inertia constant) peak period Tp of the sea state reference period zero crossing period of the sea state thickness (component, wall, plate) time total current velocity at level z sub surface current velocity at the still water level wind-generated current velocity at the still water level design sea current speed i% fractile value of the normal distribution

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Symbol and Units

IV Part 2 GL 2012

Symbol U u(10m,1 hour) uR uD V V V (y, z, t) V (z) VA Vave Vcg VeN VgustN Vhub Vin VN Vout Vr Vref VT vboat W w X x; x x x xm xr xs y y; y YNT z z zhub z; z ZNT

Meaning voltage hourly mean wind speed at 10m height water particle velocity for deep water waves water particle design velocity volume wind speed longitudinal component of the wind speed as a function of h orizontal distance to hub, height and time magnitude of the wind speed at the height z short-term cut-out wind speed annual average wind speed at hub height extreme coherent gust magnitude expected extreme wind speed (averaged over 3s), with a recurrence period of Nyears. maximum value of the wind speed for the extreme operating gust, with an expected recurrence period of N years 10-min mean of the wind speed at hub height cut-in wind speed expected extreme wind speed (averaged over 10min), with a recurrence period of N years cut-out wind speed rated wind speed reference wind speed. Corresponds to the 10-min mean of the extreme wind speed with a recurrence period of 50 years at hub height wind speed at hub height for maintenance, erection and transport (averaged over 10min) boat impact speed section modulus of a plane displacement in the z direction reactance coordinates fetch profile shift coeffient magnetization reactance rotor reactance stator reactance horizontal distan